Implantable cardioverter defibrillators (ICDs) typically sense a cardiac electrogram (EGM) signal using an intracardiac electrode for sensing cardiac signals (e.g. R-waves) and detecting arrhythmias. The sensitivity used for sensing cardiac event signals such as R-waves and fibrillation waves is typically set to a high sensitivity (i.e., a low setting, e.g. 0.3 mV) such that low amplitude fibrillation signals can be sensed. Such high sensitivity, however, can lead to oversensing of T-waves or other non-cardiac signals resulting in false detections of ventricular tachycardia or fibrillation. Reduced sensitivity to avoid oversensing, however, may result in undersensing of fibrillation signals. As such, a need remains for a method for cardiac signal sensing in ICDs that enables high sensitivity sensing for proper detection of arrhythmias while reducing the likelihood of oversensing that can lead to false arrhythmia detections.